Technically speaking, ONS no longer applies RPI to anything anyway, but stand by for CPIH.
From March of this year.
Two new inflation measures ? will either be used for pensions? | Towers Watson - Towers Watson
The Government has previously said that it would consider whether to base some pension increases on CPIH inflation rather than on CPI inflation once CPIH became available. Last week, the ONS said that throughout the seven years to 2012 CPIH inflation was always lower than or the same as CPI inflation. It was on average been 0.2 per cent lower and this was also the gap at the end of 2012.